Process for production of polyethylene

ABSTRACT

A novel process for production of polyethylene comprises polymerizing ethylene or a mixture of ethylene and a copolymerizable comonomer in the presence of a Ziegler-type catalyst at a pressure of 200 atm or more and at a temperature of 125° C. or more, wherein an organic peroxide is added to the resulting polymerization product taken out of a reaction zone to deactivate the remaining catalyst. Formation of undesired oligomers or low-molecular polymers is prevented because the reaction does not proceed in the polymerization product taken out of the reaction zone. There is almost no retardation of the polymerization reaction even by the recycled use of the monomer separated and collected from the polymerization product.

This is a continuation of application Ser. No. 06/840,545, filed Mar.17, 1986, now U.S. Pat. No. 4,719,270 which is a continuation ofabandoned application Ser. No. 506,588 filed June 22, 1983, nowabandoned.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

This invention relates to a novel continuous process for production ofpolyethylene. More particularly, this invention relates to an improvedprocess for production of polyethylene in the presence of a Ziegler-typecatalyst at high temperature and high pressure.

Hitherto, polymerization and copolymerization of ethylene have beencarried out by the use of a conventional catalyst at a pressure of 200atmospheres or more and at a temperature of 125° C. or more. In suchprocesses, the resulting reaction mixture is introduced into at leastone separator when it comes out of a polymerization reactor. Thisseparator is operated to separate ethylene (and any other monomer) fromthe polymer produced in the reactor in one or more steps. In general,the pressure in the first separator is selected to be 500 atmospheres orless.

When a Ziegler-type catalyst is used in the polymerization reactor inthe conventional processes, polymerization (homo- or co-polymerization)or oligomerization of monomer (or monomers) occurs successively underthe above mentioned operating conditions of the separator (e.g.,temperature, pressure, residence time, etc.), which results in formationof undesired products such as low-molecular products and waxy products,and the like.

The present invention aims to avoid such undesirable results.

(2) Prior Art

In the low-pressure polymerization of α-olefins in the presence of aZiegler-type catalyst, it has been known to terminate the reaction byadding to the reaction mixture a variety of reaction agents such asalcohols, epoxides or alkali metal hydroxides.

Thus, it would be readily considered by those skilled in the art to adda polymerization inhibitor or a catalyst-decomposition agent to thereaction mixture to prevent polymerization or oligomerization in theabove mentioned separator.

In industrial plants operated at high pressure and temperature, however,an unreacted monomer or monomers are normally recycled for reuse. If theconventional reactive agent mentioned above in an amount sufficient todeactivate the catalyst should be added at the outlet of the reactor orthe inlet of the separator, the reactive agent will also be recycledinto the polymerization reactor to retard the polymerization reaction.

In this connection, there is proposed as shown in Japanese Laid-OpenPatent Specification No.11182/76 a method for preventing retardation ofthe recycling polymerization reaction wherein a solid alkali metal orsolid salt thereof is used as a reactive agent, and the resultingreaction mixture of the metal salt and the catalyst is caused to remainin the resulting polymer.

The alkali metal or salt thereof is insoluble in a non-polar hydrocarbonsolvent which is sometimes used as a polymerization dispersion medium.Thus, it is very difficult to add such an agent to a high-pressureregion such as the position just before the outlet valve of thepolymerization reactor or the inlet of the separator. Furthermore, theadditive agent is solid and thus has poor reactivity with the catalyst.In this case, in order to deactivate the catalyst completely, it isgenerally necessary to use the additive agent in an amount of 1 or moregram equivalent of the alkali metal contained in the metal salt per thesum of aluminum and titanium in the gram atom contained in the catalyst.

SUMMARY OF THE INVENTION

In order to produce polyethylene with a Ziegler-type catalyst at hightemperature and pressure and to prevent formation of undesired products,we have conducted research on a novel reactive agent which caneffectively prevent formation of the undesired products, can be readilyadded to a high-pressure region, and will not retard the polymerizationreaction as a result of recycled use of an unreacted monomer and havethus developed the present invention.

The process for production of polyethylene in accordance with thepresent invention comprises introducing a feed material containingethylene or a monomer material consisting of ethylene and a comonomorcopolymerizable therewith in a non-batchwise fashion into apolymerization zone which is maintained at a pressure of 200 atmospheresor more and at a temperature of 125° C. or more and also is under theaction of a catalyst comprising a transition-metal derivative and anorganoaluminum derivative, causing polymerization of the monomer, takingthe resulting polymerization product out of the polymerization zone in anon-batchwise fashion, and separating the resulting polymer from theunreacted monomer to recover the polymer, the process beingcharacterized is that an organic peroxide is added to the polymerizationproduct which is removed from the reaction zone before the step ofrecovering the polymer to deactivate the remaining catalyst.

The catalyst-deactivator to be used in the present invention can exhibita catalyst-deactivation effect in a small quantity because thedeactivator is an organic peroxide and thus is soluble in thepolymerization product taken out of the polymerization zone.Furthermore, poisoning of the catalyst is not observed even whenpolymerization product residue after recovering the polymer, such as theunreacted monomer and (or) polymerization dispersion medium, is reusedin the polymerization zone. It is assumed that the organic peroxideadded is decomposed and converted to substances which are catalyticallynon-poisonous (e.g., reaction product of the peroxide itself or reactionproduct thereof with the catalyst), because the peroxide reacts with theactive catalyst present in the polymerization product, or thepolymerization product removed from the polymerization zone is still inthe state of high temperature and pressure. It is to be understood,however, that the present invention is not restricted by suchassumption.

Industrial advantages as given below are obtained in accordance with thepresent invention.

(1) Side reactions which for undesired high-molecular products such asgrease or wax, which may occur at the outlet of the reactor orsucceeding apparatus parts, can be avoided.

(2) Other possible side reactions, such as formation of oligomers due todimerization reaction or the like of ethylene or other monomers can alsobe avoided.

(3) Recycled use of the unreacted gas does not have an adverse effect onthe polymerization reaction, and thus continuous production can besuccessfully carried out.

BRIEF DESCRIPTION OF THE DRAWING

In the accompanying drawing, the single figure is a flow sheet showingone mode of practice of the present invention.

DETAILED DESCRIPTION OF THE INVENTION 1. Polymerization at hightemperature and high pressure 1) Definition

As described above, polymerization of ethylene at high temperature andpressure by the use of a Ziegler-type catalyst is well known in the art.

More specifically, the conventional process for polymerization relevantto the present invention comprises introducing a feed materialcontaining ethylene or a monomer material consisting of ethylene and amonomer copolymerizable therewith in a non-batchwise fashion into apolymerization zone which is maintained at a pressure of 200 atmospheresor more and a temperature of 125° C. or more and is also under theaction of a catalyst comprised of a transition-metal derivative and anorganoaluminum derivative, taking the resulting polymerization productout of the polymerization zone in a non-batchwise fashion, andrecovering the resulting polymer.

2) Catalyst

The term "comprised of a transition-metal derivative and organoaluminumderivative" means that the catalyst may contain carriers, electrondonors and other auxiliary components in addition to the essential twocomponents and also can be prepared by any method known in the art.

The catalyst used is selected from those which belong to the category ofso-called Ziegler-type catalysts and are composed of a combination ofthe following components A and B.

(1) Component A

The component A is an organometallic compound.

The organometallic compound used as a cocatalyst in the presentinvention may be selected from organometallic compounds of metals ofGroups I to III of the periodic table which are known as cocatalysts forthe Ziegler-type catalysts. Particularly, organoaluminum compounds arepreferable.

The organoaluminum compounds include those which have the formula:

    R.sup.3.sub.3-p AlX.sub.p.sup.1,

wherein: R¹ represents hydrogen or a hydrocarbon residue having 1 to 20carbon atoms, preferably, 1 to 6 carbon atoms; X¹ represents hydrogen,halogens or an alkoxy group having 1 to 20 carbon atoms, preferably, 1to 6 carbon atoms; and p represents a value of 0≦p≦2, preferably,0<p≦1.5. Examples of such an organoaluminum compound are (a)trialkylaluminums such as trimethylaluminum, triethylaluminum,triisobutylaluminum, trioctylaluminum and tridecylaluminum; (b)dialkylaluminum monohalides such as diethylaluminum monochloride anddiisobutylaluminum monochloride; (c) alkylaluminum sesquihalides such asethylaluminum sesquihalide; (d) dialkylaluminum hydrides such asdethylaluminum hydride and diisobutylaluminum hydride; and (e)alkylaluminum alkoxides such as diethylaluminum ethoxide,diethylaluminum butoxide and diethylaluminum phenoxide.

These organoaluminum compounds of items (a) through (e) may be usedsingly or in mixtures of two or more of these compounds. In thepolymerization under high temperature and pressure according to thepresent invention, a dialkylaluminum monohalide or an organoaluminumcompound mixture of a dialkylaluminum monohalide with an organoaluminumcompound of item (a), (c), (d) or (e) is preferably used. With regard tothe amount of the organoaluminum compounds used, there is no specificlimitation. However, it is desirable that the organoaluminum compound beused in a quantity such that the atomic ratio of Al/Ti with respect to asolid catalyst component as described hereinafter is in the range offrom 3 to 200, preferably from 6 to 20.

As the component B, a transition-metal compound which has been generallyemployed in a Ziegler-type catalyst can be used.

From the viewpoint of catalytic activity, etc., however, the followingcomponent is preferably used

(2) Component B

The component B is a contact product of a magnesium compound defined asa component (a) and a titanium compound defined as a component (b).

a) Magnesium compound

A magnesium compound which is suitable for use in the present inventionis any of magnesium compounds in the form of a solid or a liquid.

Examples of such a magnesium compound are i) magnesium halides such asmagnesium dichloride, magnesium dibromide and magnesium diiodide; ii)halohydrocarbyloxymagnesiums such as magnesiumethoxychloride andmagnesiumhydroxychloride; iii) magnesium dialcoholates such as magnesiumdiethoxide and magnesium dimethoxide; iv) magnesium oxide and magnesiumcarbonate, and v) organomagnesium compounds such as diethylmagnesium andethylmagnesium chloride. Among these, the magnesium compounds of items(i), (ii) and (v) are preferable; and magnesium dichloride isparticularly preferable. It is desirable that the solid magnesiumcompound have a specific surface area of at least 5 m² /g for thepurpose of providing a highly active catalyst.

As the magnesium compound, use may also be made of those obtained bysubjecting magnesium halides, such as magnesium dichloride, todissolution in a suitable solvent and then to re-precipitation from thesolution. Such re-precipitated magnesium compounds can be prepared bydissolving a magnesium halide in the presence or absence of an organicsolvent in a medium selected from alcohols ROH wherein R represents ahydrocarbon residue having 3 to 10 carbon atoms; ethers R-O-R' therein Rand R' represent a hydrocarbon residue having 2 to 8 carbon atoms, or Rand R' form a ring system containing a 5-to 8-membered ring; phosphoricesters PO(OR)₃ wherein R represents a hydrocarbon residue having 2 to 10carbon atoms; and titanic acid esters Ti(OR)₄ wherein R represents ahydrocarbon residue having 3 to 10 carbon atoms and by adding ahalogenating agent such as TiCl₄ and SiCl₄ or a reducing agent such asan alkylsiloxane or a derivative thereof to the resultant solutionthereby to cause re-precipitation.

b) Titanium compound

A titanium compound suitable for the present invention is selected fromhalides, oxynalides, alcoholate and alkoxyhalides of titanium. Examplesof these compounds are as follows.

i) Compounds of tetravalent titanium

TiCl₄, TiBr₄, Ti(OC₂ H₅)Cl₃, Ti(O-n-C₄ H₉)₃ Cl, and Ti(O-n-C₄ H₉)₄.

ii) Compounds of trivalent titanium

TiCl₃, TiBr₃, and Ti(OC₂ H₅)Cl₂.

When a tetravalent titanium compound in the form of a liquid is used inthe polymerization under high temperature and pressure according to thepresent invention, the resulting catalyst exhibits a high catalyticactivity which leads to the production of a desirable copolymer.

The above mentioned magnesium compound and titanium compound areessential components in the present invention. The component B maycontain an auxiliary component, if necessary. The use of an auxiliarycomponent may be effective for further enhancing the uniformity of theresulting copolymer. Examples of auxiliary components are electrondonors such as alcohols, ethers and esters; metal halide compounds suchas SiCl₄ and AlCl₃ ; and polysiloxanes such as alkylhydropolysiloxanesand dialkylpolysiloxanes. A suitable method of using these auxiliarycomponents is described in concrete terms in Japanese Patent ApplicationLaid-Open Nos. 55-21435 and 55-40745.

Contact condition

The contact between the component (a) and the component (b) may becarried out under any conditions conventionally known. However, it isdesirable that the contact of these components with each other becarried out at a temperature of from -50° to 200° C., in general. Thecontact time is usually in a range of from about 10 minutes to about 5hours. It is preferable that the contact between the components (a) and(b) be carried out with stirring. The use of a mechanical pulverizationmeans such as a ball mill or a vibration mill may serve to afford a morethorough contact between the components (a) and (b).

The contact between the components (a) and (b) may also be carried outin the presence of a dispersion medium. Examples of suitable dispersionmediums for the contact are hydrocarbons, halogenated hydrocarbons anddihydrocarbylpolysiloxanes. Examples of hydrocarbons are hexane,heptane, benzene, toluene and cyclohexane. Examples of halogenatedhydrocarbons are n-butyl chloride, 1,2-dichloroethane, chloroform,carbon tetrachloride, o-chlorotoluene, m-chlorotoluene, p-chlorotoluene,benzyl chloride, benzylidene chloride and iodobenzene. Examples ofdihydrocarbylpolysiloxanes are dialkylpolysiloxanes such asdimethylpolysiloxane and methylphenylpolysiloxane.

Quantity ratio

The quantity of each component used may be arbitary as long as theadvantages of the present invention can be attained. Generally, thefollowing range is preferable. The mole ratio of Mg/Ti, on which thequantity ratio of the component (a) to the component (b) depends, is inthe range of, ordinarily, from 0.5 to 50, preferably, from 1 to 20.

(3) Quantity ratio between components A and B

The quantity ratio between the components A and B is not basicallylimited but is preferably within the range of 3 to 200, particularly 6to 20, in terms of the Al/Ti atomic ratio.

(4) Preparation of catalyst

The catalyst is prepared by combining the components A and B within oroutside the polymerization zone. The component A alone or a combinationof the components A and B is injected into the polymerization zone undera high pressure by means of a high-pressure pump. For this reason, thesecomponents should be in the form of a liquid, or fine powder or itsslurry and, if they are powdery, their particle size should preferablybe of the order of 10μ or less, particularly of the order of 1 to 5μ.

3) Monomers

The "monomer" to be polymerized in the presence of the above mentionedcatalyst is ethylene or a mixture of ethylene and a comonomercopolymerizable therewith.

In this case, the comononers include, for example, an α-olefin such aspropylene, butene-1, hexene-1, 4-methylpentene-1 and octene-1. Thequantity of the comonomer is normally such that the amount of thecomonomeric component contained in the resulting polymer will be about 0to about 20% by weight.

Thus, the quantity of the comonomer fed together with ethylene forpolymerization is generally 0 to 10 parts and preferably 0.3 to 5 partsby volume per 1 parts by volume of ethylene.

Accordingly, the term "monomer" used herein encompasses both ethyleneand a mixture thereof with a comonomer. Thus, the term "polyethylene"herein encompasses both ethylene homopolymer and ethylene copolymer.Also, the term "polymerization" herein encompasses bothhomopolymerization and copolymerization.

(4) Polymerization operation

The polymerization apparatus which is maintained at a specifictemperature and a specific pressure and also accommodates apolymerization zone under the action of the above mentioned catalyst maybe an internally stirring-type autoclave reactor, a tubular reactor, acombination apparatus of the autoclave reactor and the tubular reactor,or some other suitable reactor.

The monomer is polymerized by introducing a feed material containing themonomer into the apparatus in a non-batchwise fashion. The term "a feedmaterial containing the monomer" used herein means a feed materialcomprising the monomer and a polymerization dispersion medium and (or) acatalyst and (or) molecular weight-modifying hydrogen, etc. Thesecomponents constituting the feed material can be in the state ofcoexistence or non-coexistence.

The term "in a non-batchwise fashion" herein means a continuous fashionor an intermittent fashion.

The polymerization product taken out of the polymerization zone in anon-batchwise fashion, which comprises polymer, unreacted monomor,hydrogen, a polymerization dispersion medium, etc., is then sent to amonostep or multistep separator, where the polymerization product issubjected to the condition of reduced pressure or a lower temperature torecover the resulting polymer. After the recovery of the polymer, ifnecessary, a desired component is recovered or separated from thepolymerization product. Then the remaining components are ordinarilyrecycled to the polymerization zone. The meritorious effect of thepresent invention, however, can be obtained even when the remainingcomponents of the polymerization product from which the polymer has beenrecovered are not recycled into the polymerization zone becausedeactivation of the catalyst with organic peroxides is effective forpreventing the formation of side-reaction products (e.g., forcontrolling the formation of oligomers).

One example of the apparatus suitable for use in the present inventionis shown in FIG. 1.

Ethylene or a gaseous mixture of ethylene and a comonomer for thepolymerization is compressed in a first compressor 1, re-compressed in asecond compressor 2 to a pressure as high as or somewhat higher than thepolymerization pressure, adjusted to a specific temperature by a heatexchanger 3 and then introduced into a reactor 4 for polymerizationreaction.

The polymerization product obtained via polymerization reaction in thereactor 4 is taken out of the bottom of the reactor 4 and separated intopolymer and unreacted monomer in a high-pressure separator 5. Theresulting polymer is separated from the unreacted monomer, oligomer andthe like in a low-pressure separator 6 and then introduced into apelletizer 7 to be formed into pellets.

The unreacted monomer separated and collected by the high-pressureseparator 5 is cooled in coolers 8, 9, separated from low-molecularpolymers and oligomer by drain separators 10, 11, mixed with a monomersupplied via a filter 12, and reused for polymerization.

Preferred ranges of the polymerization conditions, etc. are shown below.

(1) Polymerization conditions

(i) Polymerization pressure

The pressure used in the polymerization process is more than 200 kg/cm²,preferably, from 500 to 4,000 kg/cm², more preferably, from 700 to 3,000kg/cm².

(ii) Polymerization temperature

The polymerization temperature is at least 125° C., preferably, in therange of from 150° to 350° C., more preferably, from 200° to 320° C.

(2) High-pressure separator

The separator is operated at a pressure of generally 100 to 350 kg/cm²,preferably 180 to 250 kg/cm², and at a temperature of generally 150° to300° C., preferably 200° to 250° C.

(3) Low-pressure separator

The separator is operated at a pressure of generally 0 to 5 kg/cm²,preferably 0.5 to 3 kg/cm² and at a temperature of generally 150° to300° C., preferably 180° to 250° C.

2. Treatment with catalyst-deactivators

In the process for polymerization at high temperature and high pressureas described above, the present invention is characterized in that thecatalyst is deactivated by adding organic peroxides to thepolymerization product (the resulting polymer and unreacted monomer)removed from the reaction zone.

Deactivation of the catalyst presumably results from destruction of atleast one of the two essential components of the catalyst describedabove.

1) Organic peroxides

As the organic peroxides for the present invention, most of theperoxides which have been employed as a radical catalyst for producingthe so-called high-pressure polyethylene can be used.

Specific examples of such compounds include diacylperoxides such asacetylperoxide, isobutylperoxide, and 3,5,5-trimethylhexanoylperoxide;dialkylperoxides such as di-tert-butylperoxide; peroxyesters such ast-butylperoxyacetate, t-butylperisobutyrate and t-butylperoxypivalate;ketone peroxides such as methyl ethyl ketone peroxide; peroxyketal suchas 1,1-bis(t-butylperoxy)cyclohexane; hydroperoxides such asparamenthane hydroperoxide; peroxy dicarbonates such as diisopropylperoxydicarbonate and di-2-ethylhexyl peroxydicarbonate; andacetylcyclonexyl sulfonyl peroxide. It is preferable that the organicperoxides have a decomposition temperature in the range of 60° to 180°C., preferably 90° to 150° C., the decomposition temperature hereinmeaning the temperature at which half of the quantity of the organicperoxide is decomposed in one minute. Among others, peroxyesters,diacylperoxides and peroxydicarbonates which have a decompositiontemperature of the above mentioned range are especially preferred. Theamount of the organic peroxides to be used should be sufficient todeactivate the catalyst without fail. In general, it is desirable withrespect to this amount that the ratio of the organic peroxide in mols toaluminum and titanium in gram atom contained in the catalyst be in therange of from 0.02 to 0.8 and preferably from 0.08 to 0.20.

The organic peroxide is normally added in the form of a solutionthereof, e.g., the solution in a hydrocarbon. A paraffin, an olefin oran aromatic or alicyclic hydrocarbon having 6 to 20, preferably 6 to 12carbon atoms can be as the hydrocarbon. Preferred are hexane, heptane,octane, decane, toluene and xylene. In this case, the concentration ofthe peroxide in the hydrocarbon is generally in the range of 0.01 to 95%by weight, preferably in the range of 1 to 10% by weight.

2) Addition of organic peroxides and treatment

The organic peroxide is added to the polymerization product remove fromthe polymerization zone. From the viewpoint of preventing a sidereaction due to the still active catalyst, it is preferable to add theperoxide immediately after the product has been removed from thepolymerization zone. Thus, the organic peroxide is preferably added atthe position nearest to the outlet valve outside of the polymerizationreactor, e.g., at the point A shown in FIG. 1. When the polymerizationzone is not adjacent to the outlet valve in the polymerization zone, theperoxide can also be added in the polymerization reactor to thepolymerization product (which has, of course, been taken out of thepolymerization zone).

Treatment with the organic peroxide is generally conducted underconditions which are milder than the temperature and pressure conditionsin the polymerization zone. However, in view of the recycling of theremaining polymerization product (after recovering the resultingpolymer), the conditions will be higher than room temperature andatmospheric pressure. In general, the ordinary treatment conditions areapproximately a temperature of 125° to 250° C., preferably, 150° to 250°C. and a pressure of 150 to 2,500 atmospheres. In order to obtain goodcontact between the organic peroxide and the catalyst, it is preferableto add with stirring the peroxide in the form of a relatively dilutesolution (about 1% by weight or less).

The deactivation of the catalyst with the organic peroxide can also beconducted in a multistep manner as necessary.

The treatment of the polymerization product after addition of theorganic peroxide is essentially the same as that in the conventionalprocess. As necessary, however, it is also possible to filter or distilla liquid-phase portion after removing the polymer.

3. Examples of Experiments 15 Examples 1 through 12

Polymerization (i.e. homopolymerization or copolymerization) of ethylenewas conducted under a high pressure of 900 atmospheres under theconditions given below by means of the high-pressure polymerizationapparatus for ethylene comprising an internally stirring-type autoclavereactor having an internal space of 1.5 liter, a first separator (highpressure separator) maintained at a pressure of 200 atmospheres and asecond separator (low-pressure separator) maintained at a pressure of 3atmospheres, which were connected in series.

More specifically, the reaction temperature was of the order of 240° C.,the temperature within the first separator was 210° to 240° C., and thetemperature within the second separator was 190° to 220° C. The catalystsystem used was composed of a co-pulverized mixture of MgCl₂ and TiCl₄(Ti content supported being 9% by weight) and diethylaluminum, the ratioof Al/Ti being 12. The amounts supplied of ethylene, a comonomer, andhydrogen chain transfer agent are shown in Table 1, respectively.Incidentally, unreacted ethylene (or unreacted ethylene and comonomer inthe case of copolymerization) separated from the resulting polymer inthe first separator was recycled into the polymerization apparatus.

At a position just before the take-out valve of the reactor were addedthe above mentioned organic peroxide in Examples 2, 4, 6, 8 and 10 andthe ethyl alcohol in Examples 11 and 12 for the purpose of providingcomparative examples.

The results are shown in Table 2.

In Table 1, the following items are shown in the corresponding columns,respectively.

(a) Example Nos.

(b) Pressure in the reactor (Kg/cm²)

(c) Temperature in the reactor (° C.)

(d) Amount of ethylene supplied into the reactor (Kg/Hr)

(e) Comonomers

(f) Amount of the comonomer supplied into the reactor (Kg/Hr)

(g) Amount of hydrogen supplied into the reactor (liter/Hr)

(h) Deactivator used

(i) Amount of the deactivator added (the ratio of the deactivator inmillimol to aluminum and titanium in milliator present in the catalystsupplied to the reactor)

(j) Pressure in the first separator (Kg/cm²)

(k) Temperature in the first separator (° C.)

In Table 2, the following items are shown in the corresponding columns,respectively.

(a) Example Nos.

(b) Melt index of polyethylene (g/10 minutes, according to ASTM D-1238)and density of polyethylene (g/cm³ according to ASTM D-1505)

(c) Output of polymers per hour (Kg/Hr)

(d) Activity of catalyst (g-PE/g-Ti)

(e) Amount of wax collected by the separator provided in the recyclingline of unreacted gases separated from the polymer by the firstseparator (g/Hr)

(f) Concentration of oligomers contained in the inlet gas of the reactor(% by weight, the oligomer meaning the component of C₈ or more detectedby introducing the inlet gas into an on-line gas chromatographyapparatus.)

The measurements were conducted on samples (A) taken afterpolymerization for 2 hours and samples (B) taken after polymerizationfor 10 hours. In accordance with these methods, it can be made clearthat even by recycling organic peroxides, the compounds formed in thereaction of organic peroxides and Ziegler-type catalysts, thepolymerization is not adversely affected, and undesirable side reactionsare prevented.

                                      TABLE 1                                     __________________________________________________________________________    Polymerization Conditions, etc.                                                                                Deactivators                                 Reaction     Amount                                                                             Amount of co-                                                                           Amount      amount                                                                             The first sepa-                  conditions   of ethy-                                                                           monomers  of          deacti-                                                                            rator                            Exam-                                                                             pressure                                                                           temp.                                                                             lene gas   amount                                                                            hydrogen    vator/                                                                             pressure                                                                           temp.                       ple Kg/cm.sup.2                                                                        °C.                                                                        Kg/Hr                                                                              species                                                                             Kg/Hr                                                                             Nl/Hr                                                                              species                                                                              Al + Ti                                                                            kg/cm.sup.2                                                                        °C.                  __________________________________________________________________________    1   900  240 16   propylene                                                                           24  5    --     --   200  220                         2   900  240 16   propylene                                                                           24  5    di-2-ethyl-                                                                          0.1  200  220                                                          hexyl peroxy-                                                                 dicarbonate                                  3   900  240 16   1-hexene                                                                            35  2    --     --   200  210                         4   900  240 16   1-hexene                                                                            35  2    t-butyl-                                                                             0.15 200  210                                                          peroxy-                                                                       pivalate                                     5   900  240 30   --    --  40   --     --   200  240                         6   900  240 30   --    --  40   acetyl-                                                                              0.12 200  240                                                          peroxide                                     7   900  240 16   1-Butene                                                                            30  5    --     --   200  220                         8   900  240 16   1-Butene                                                                            30  5    Octanoyl                                                                             0.13 200  220                                                          peroxide                                     9   900  260 16   1-Hexene                                                                            17  5    --     --   200  220                         10  900  260 16   1-Hexene                                                                            17  5    t-Butylperoxy                                                                        0.12 200  220                                                          isobutyrate                                  11* 900  240 16   propylene                                                                           24  5    ethanol                                                                              0.1  200  220                         12* 900  240 16   propylene                                                                           24  5    ethanol                                                                              0.5  200  220                         __________________________________________________________________________     Note:                                                                         *Comparative example                                                     

                                      TABLE 2                                     __________________________________________________________________________    Results of Polymerization                                                                           Catalytic                                                                           Amount of                                                                           Concentration of                                    MFR  Density                                                                            Output                                                                            activity                                                                            wax   oligomers                                   Examples                                                                              g/10 min.                                                                          g/cm.sup.3                                                                         Kg/Hr                                                                             g-PE/g-Ti                                                                           g/Hr  % by weight                                 __________________________________________________________________________    1    A**                                                                              1.1  0.9205                                                                             7.2 167,000                                                                             420   not more than 1                                  B**                                                                              1.2  0.9200                                                                             7.3 169,000                                                                             452   6                                           2   A   0.9  0.9205                                                                             7.0 162,000                                                                              .sup.. 5.                                                                          not more than 1                                 B   1.0  0.9205                                                                             7.4 171,000                                                                              6    "                                           3   A   1.2  0.9195                                                                             8.6 299,000                                                                             430   not more than 1                                 B   1.3  0.9210                                                                             8.7 302,000                                                                             565   12                                          4   A   1.1  0.9190                                                                             8.4 292,000                                                                              12   not more than 1                                 B   1.2  0.9190                                                                             8.5 295,000                                                                              15   "                                           5   A   4.2  0.9560                                                                             5.4 250,000                                                                             280   not more than 1                                 B   4.6  0.9550                                                                             5.3 245,000                                                                             334   4                                           6   A   4.0  0.9560                                                                             5.2 241,000                                                                              3    not more than 1                                 B   4.2  0.9560                                                                             5.3 245,000                                                                              3    "                                           7   A   1.6  0.9220                                                                             7.6 287,000                                                                             360   not more than 1                                 B   1.8  0.9215                                                                             7.8 294,000                                                                             410   8                                           8   A   1.6  0.9220                                                                             7.6 285,000                                                                              8    not more than 1                                 B   1.4  0.9220                                                                             7.8 297,000                                                                              6    "                                           9   A   12   0.9290                                                                             9.6 273,000                                                                             520   2                                               B   14   0.9280                                                                             9.5 265,000                                                                             675   14                                          10  A   12   0.9285                                                                             9.5 263,000                                                                              24   not more than 1                                 B   13   0.9290                                                                             9.4 266,000                                                                               26. "                                           11* A   1.2  0.9205                                                                             7.1 164,000                                                                             392   not more than 1                                 B   1.4  0.9210                                                                             6.5 129,000                                                                             405   5                                            12**                                                                             A   1.3  0.9200                                                                             7.2 125,000                                                                             250   not more than 1                                 B   1.8  0.9220                                                                             6.8  76,000                                                                             280   3                                           __________________________________________________________________________     Note:                                                                         *Comparative example                                                          **Sample A taken 2 hours after commencing polymerization                      Sample B taken 10 hours after commencing polymerization                  

What is claimed is:
 1. A process for the high pressure production ofcopolymers of ethylene, which comprises:(a) introducing a feed materialcomprising ethylene and a comonomer copolymerizable therewith in anon-batchwise manner into a polymerization zone which does not contain adispersant, which is maintained at a pressure of at least 200atmospheres and at a temperature of 150°-320° C. and which contains acatalyst comprised of a titanium compound and an organoaluminumderivative combined in such amounts that the atomic ratio Al/Ti rangesfrom 6-20; (b) polymerizing the monomer reactants in a nonbatchwisemanner; (c) withdrawing polymerized material at a temperature of150°-250° C. from said polymerization zone and adding from 0.08-0.20mole of t-butylperoxypivalate per gram atom of the sum of the gram atomsof aluminum and titanium in said catalyst, to said withdrawnpolymerization material in order to deactivate the catalyst therein; (d)separating the polymer product component of the withdrawn material fromany unreacted monomer under superatmospheric pressure, thereby affectingpolymer product recovery; and (e) recycling the separated unreactedmonomer of step (d) to said polymerization zone.
 2. The processaccording to claim 1, wherein said comonomer is propylene, butene-1,hexene-1,4-methylpentene-1 or octene-1.
 3. The process according toclaim 1, wherein the amount of said comonomer ranges from 0 to 10 partsby volume per volume part of ethylene.
 4. The process according to claim1, wherein the t-butyperoxypialate is supplied to step (c) in the formof an organic hydrocarbon solution at a concentration of 0.01% to 95% byweight.
 5. The process according to claim 1, wherein thet-butylperoxypivalate is added to the withdrawn polymerization productwhich is under a pressure of at least 150 atmospheres.
 6. The processaccording to claim 1, wherein said separation step (d) is a two-stepseparation process of a first high pressure separation step conducted ata pressure of 100 to 350 kg/cm², followed by a low pressure separatorstep operated at a pressure of 0 to 5 kg/cm².